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author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2017-04-11 18:25:08 -0400 |
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committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2017-04-17 15:21:19 -0400 |
commit | b980b117c9ff17226937128a15692a18c9a28ed6 (patch) | |
tree | f4f1d2911131998ea103c58846b516ce4c039bbf | |
parent | fcdc71257923263d042236eaf62bae5e033757b5 (diff) | |
download | linux-b980b117c9ff17226937128a15692a18c9a28ed6.tar.bz2 |
tracing: Have the trace_event benchmark thread call cond_resched_rcu_qs()
The trace_event benchmark thread runs in kernel space in an infinite loop
while also calling cond_resched() in case anything else wants to schedule
in. Unfortunately, on a PREEMPT kernel, that makes it a nop, in which case,
this will never voluntarily schedule. That will cause synchronize_rcu_tasks()
to forever block on this thread, while it is running.
This is exactly what cond_resched_rcu_qs() is for. Use that instead.
Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
-rw-r--r-- | kernel/trace/trace_benchmark.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/kernel/trace/trace_benchmark.c b/kernel/trace/trace_benchmark.c index e49fbe901cfc..16a8cf02eee9 100644 --- a/kernel/trace/trace_benchmark.c +++ b/kernel/trace/trace_benchmark.c @@ -153,10 +153,18 @@ static int benchmark_event_kthread(void *arg) trace_do_benchmark(); /* - * We don't go to sleep, but let others - * run as well. + * We don't go to sleep, but let others run as well. + * This is bascially a "yield()" to let any task that + * wants to run, schedule in, but if the CPU is idle, + * we'll keep burning cycles. + * + * Note the _rcu_qs() version of cond_resched() will + * notify synchronize_rcu_tasks() that this thread has + * passed a quiescent state for rcu_tasks. Otherwise + * this thread will never voluntarily schedule which would + * block synchronize_rcu_tasks() indefinitely. */ - cond_resched(); + cond_resched_rcu_qs(); } return 0; |